Convertible racket for multiple stringing configurations

ABSTRACT

The present invention is a game racket with string supports strategically positioned to support at least two different stringing configurations, so that a first subset of some or all of said string supports, when strung, results in a racket strung in one stringing configuration and a second subset of some or all of said string supports, when strung, results in a second stringing configuration. In a preferred embodiment of the present invention, the game racket has a plurality of indicia effective to guide the stringing of each of the various stringing patterns.

CONTINUATION-IN-PART

This application is a Continuation-in-Part of U.S. patent application Ser. No. 10/436,173 filed on May 12, 2003, and is a non-provisional, Utility Patent Application claiming priority of Provisional Patent Application No. 60/763,145 filed on Jan. 28, 2006.

TECHNICAL FIELD

The present invention relates to sports rackets and, more particularly, to string support arrangements for sports rackets.

BACKGROUND OF THE INVENTION

Different types of stringing patterns have different total and individual string lengths, different intersecting angles of the strings, and different inter-string spacings. Each stringing pattern provides playing characteristics and advantages unique to each specific stringing pattern or configuration. Some racket stringing patterns are very soothing to the arm and provide comfort and protection when the arm is injured, whereas other stringing patterns provide greater spin and more control. Some racket stringing patterns do not provide comfort to the arm but instead provide more power. Some racket stringing configurations provide power, control, as well as comfort to the arm.

The racket of the present invention is a structural engineering development that enables a racket to be strung in more than one stringing configuration.

The racket of the present invention provides a player with the opportunity to evaluate multiple stringing patterns, and decide which stringing pattern they prefer, with the purchase of a single racket. Different stringing patterns produce different performance characteristics in a racket. Heretofore, a player could only evaluate the effect of various stringing configurations (patterns) by purchasing a separate racket for each stringing pattern to be evaluated. Because the racket of the present invention can be strung in a plurality of stringing patterns, a player can now evaluate the effect of various stringing patterns on their play without having to buy multiple rackets.

Additionally, a player may decide to use one type of stringing pattern on one day and another type on another day. The stringing pattern on the racket of the present invention can be readily modified, by restringing, to accommodate the player's stringing pattern preferences.

The racket of the present invention increases the marketability of rackets strung in a non-conventional pattern as the versatility factor of this product will appeal to a broader audience. The racket of the present invention is especially suitable for those who would like to try a diagonally-strung racket, but do not want to buy a new racket with such diagonal stringing, if after testing it they decide they prefer a conventional stringing pattern, with which they are more familiar with ball responses and the playability. In general, a diagonally-strung racket has two opposing sets of intersecting diagonal strings, each oblique to the handle of the racket. Typically, the characteristics of diagonal stringing are: added spin, control, power and reduced vibration, and the stringing lasts longer than conventionally strung rackets.

The racket of this invention may also appeal to those who are used to a conventional stringing pattern yet want to purchase this racket in case, in the future, they may want to experiment with trying out another stringing pattern. In general, a conventional stringing pattern has one set of horizontal strings and one set of vertical strings. The two sets of strings in a conventional stringing pattern generally intersect at orthogonal angles (90 degrees). Typically, rackets strung with orthogonal stringing have two sets of strings (one longer vertical set and one shorter horizontal set) that are very different in length from each other and the individual difference in the string lengths causes undue vibration to be transmitted to the player's hand, wrist, elbow, arm and shoulder, as unequal string lengths vibrate at unequal frequencies and the dispersion of the impact of the ball hitting the strings is unbalanced along the horizontal and vertical axes.

The racket of this invention will also appeal to players wanting a racket that has the capability of being strung in more than one pattern. For instance, the racket of the present invention can be useful to use, or test out, a diagonal pattern on some occasions, and use, or test out, a conventional pattern on other occasions. Additionally, the racket of the present invention can be a useful purchase for a player who likes to use a racket which is diagonally-strung, but is worried that certain stringers in various locations might not know how to string a diagonally-strung racket. If a string breaks, on the racket of the present invention, while such a player is on a trip to a place where none of the stringers can re-string the racket in a diagonal stringing pattern, the racket of the present invention can also be easily strung in a conventional stringing pattern. Since most stringers can string a racket in a conventional pattern, the player can continue to play until they find a stringer who can string the racket in the diagonal stringing pattern which they prefer.

Another embodiment of the present invention is that the present invention can accommodate a three-directional, or four-directional stringing patterns as alternative stringing patterns. For example, a racket according to the present invention can be designed to be strung with two sets of diagonals strings interwoven with a single set of horizontal strings, or alternatively, a racket could be strung in a configuration of two sets of diagonals strings interwoven with one set of vertical strings, or potentially with four interwoven sets of interwoven strings; namely two opposing diagonal sets, one vertical set and one horizontal set of strings.

The design and versatility of the racket of the present invention differs from prior rackets. The racket of the present invention can readily utilize more than one stringing pattern on a single racket. Because of the several problems solved in the creation of a racket that can be strung in more than one way and still maintain a non-distorted shape, the present invention was (and is) not obvious to those skilled in the art of making tennis rackets. The racket of the present invention is structurally designed to accommodate more than one stringing pattern. In a preferred embodiment, the racket of the present invention is marked with indicia, accordingly, to alert the player and educate the stringer that the option of stringing the frame in multiple configurations is available. Such indicia are desirably easy to navigate and designed to guide the stringer through the stringing process so the stringing can be completed. Marketing and promotional material would also include information regarding the fact that the racket of the present invention was specifically designed to be strung in multiple stringing configurations.

It has been the experience of the present inventor that stringing a racket in a pattern other than the pattern specified by the racket manufacturer can lead to a substantial instability in the racket frame. For instance, if a conventional racket is strung diagonally at a conventionally-normal stringing tension, the width of the frame may be compressed and the length extended; or the width of the frame may be extended and the length compressed. Subsequently, the frame of a racket strung in a manner different from that specified by the racket manufacturer may crack even though the racket was strung with a conventionally-normal stringing tension, as the forces being pulled are in different directions than expected. Heretofore, rackets have not been designed to maintain their structural stability when strung in more than one stringing pattern. In contrast to the inherent structural instability of rackets previously available when such rackets were strung in a pattern other than the single pattern specified by the racket manufacturer, the racket of the present invention is structurally stable when strung in more than one stringing pattern.

Different stringing patterns disperse the impact of the ball differently. For instance, a diagonal stringing pattern has a much narrower range of string lengths than a conventionally strung racket. As a consequence of the narrower range of diagonal string lengths, the ball-racket interaction is more consistent.

The measured 16 vertical and 19 horizontal string lengths in a typical, oversize, conventionally-strung racket, were done on the commercially-available Prince 03, counting from 1^(st) left vertical on the left, sideways to the right, to last vertical; and counting from 1^(st) top horizontal, downwards to the last bottom horizontal are observed to be: 16 VERTICALS 19 HORIZONTALS  1^(st left) Vertical = 8 inches (in.)  1^(st top) Horizontal = 7.25 inches (in.)  2^(nd) = 9.5 in.  2^(nd) = 8.2 in.  3^(rd) = 11.0 in.  3^(rd) = 8.8 in.  4^(th) = 12.0 in.  4^(th) = 9.2 in.  5^(th) = 12.5 in.  5^(th) = 9.5 in  6^(th) = 12.8 in.  6^(th) = 9.7 in  7^(th) = 13.0 in.  7^(th) = 9.8 in  8^(th) = 13.0 in.  8^(th) = 9.9 in  9^(th) = 13.0 in.  9^(th) = 10.0 in 10^(th) = 13.0 in. 10^(th) = 10.1 in 11^(th) = 12.8 in. 11^(th) = 10.1 in 12^(th) = 12.5 in. 12^(th) = 10.0 in 13^(th) = 12.0 in. 13^(th) = 9.9 in. 14^(th) = 11.0 in. 14^(th) = 9.6 in. 15^(th) = 9.5 in. 15^(th) = 9.4 in. 16^(th) = 8.0 in. 16^(th) = 8.8 in. — 17^(th) = 8.3 in. — 18^(th) = 7.3 in. — 19^(th) = 6.0 in. 16 VERTICALS = total 19 HORIZONTALS = total

The measured 19 diagonal string lengths in each diagonal direction, in a typical, oversize, diagonally-strung racket, were done on the commercially-available PowerAngle Power 115. The individual measurements of the diagonal string lengths, starting at the top of the frame, and working downwards towards the last diagonal at the throat would be the identical lengths of the corresponding diagonals in the opposite direction, string for string. Namely, in said frame initially strung conventionally, then subsequently strung diagonally, said diagonal string length measurements, of each diagonal in the corresponding locations are observed to be: 19 LEFT Diagonals 19 RIGHT Diagonals  1^(st) LEFT Diagonal = 7.0 inches (in.)  1^(st) RIGHT Diagonal = 7.0 inches (in.)  2^(nd) = 8.0 in  2^(nd) = 8.0 in.  3^(rd)    9.0 in.  3^(rd) = 9.0 in.  4^(th) = 9.9 in.  4^(th) = 9.9 in.  5^(th) = 10.5 in.  5^(th) = 10.5 in.  6^(th) = 11.2 in.  6^(th) = 11.2 in.  7^(th) = 11.5 in.  7^(th) = 11.5 in.  8^(th) = 11.9 in.  8^(th) = 11.9 in.  9^(th) = 12.0 in.  9^(th) = 12.0 in. 10^(th) = 12.3 in. 10^(th) = 12.3 in. 11^(th) = 12.4 in. 11^(th) = 12.4 in. 12^(th) = 12.4 in. 12^(th) = 12.4 in. 13^(th) = 12.5 in. 13^(th) = 12.5 in. 14^(th) = 12.3 in. 14^(th) = 12.3 in. 15^(th) = 11.8 in. 15^(th) = 11.8 in. 16^(th) = 11.5 in. 16^(th) = 11.5 in. 17^(th) = 11.0 in 17^(th) = 11.0 in. 18^(th) = 10.0 in. 18^(th) = 10.0 in. 19^(th) = 9.0 in. 19^(th) = 9.0 in. 19 LEFT Diagonals = total 19 RIGHT Diagonals = total Corresponding diagonal string lengths, in opposite diagonal directions, have the same measures.

Furthermore, the range of diagonal sets of string lengths in the center of the stringing area of the racket is much narrower than is observed in the range between the center two horizontals and the center two verticals strings in a conventionally strung racket. In fact, corresponding diagonals in opposite directions are exactly equal in length. Desirably, in a diagonal stringing pattern of a racket according to the present invention, it is observed that the in the center of the stringing area of the racket, the quartile measurements of string lengths in one diagonal direction are identical to the quartile measurements of diagonals in the opposite diagonal direction. It is yet further desired that, in a diagonal stringing pattern the length of the opposing sets of diagonal strings are all the same length, whereas in conventionally-strung frames, the set of vertical strings is substantially longer than the set of horizontal strings (in this context, the word string refers to the segment of the string between two string supports and not the entire continuous string used in stringing the racket, which typically is between about 25 and 50 feet and preferably between about 35 and 45 feet).

In a conventionally strung racket, at the center portion of the stringing area the third quartile measurements of string lengths of the vertical strings are typically more than about 3 inches longer than the third quartile string length measurements of the corresponding horizontal strings.

Since the individual corresponding diagonal string lengths are equal in length, as opposed to conventional orthogonal stringing patterns where individual string lengths of the horizontals are typically shorter than the much longer vertical string segments, it has been observed that with a diagonal stringing pattern there is a more even, balanced response of the ball on the strings over the entire hitting surface of the racket head. For instance, in an oversize racket, when strung diagonally, the center two strings in each direction are the same length, that is 12 inches long. In the same racket strung conventionally, the center two vertical strings are 13 inches long while the center two horizontal strings are 10 inches long. It is even more desired that, in a diagonal stringing pattern of a racket according to the present invention, the corresponding central strings of conventionally strung frames are 3 inches different in length per string, while corresponding opposite diagonals of an oversize frame are identical in length, thus creating a more balanced, stable string bed. The corresponding two center horizontal strings and the two center much-longer vertical strings in a conventionally-strung racket are visibly unequal in length; the center two vertical strings are substantially longer than the center two horizontal strings. Furthermore, the range of string lengths observed between the individual diagonal strings is much narrower than the range of string lengths observed between individual string lengths of horizontal and vertical sets of strings in a conventionally-strung racket. It is yet further desired that, in a diagonal stringing pattern, the length of the center strings are all substantially of the same length (in this context, the word string refers to the segment of the string between two string supports and not the entire continuous string used in stringing the racket, which typically is between about 25 and 50 feet and preferably between about 35 and 45 feet), whereas in a conventionally strung racket, the central two verticals strings and the central two horizontal strings are unequal in length, and typically the vertical two central strings, and all other vertical strings, are more than about 3 inches longer than the corresponding horizontal strings in the racket, (corresponding in this context referring to the numbering of horizontal strings from top to bottom, 1^(st) to last strings, and the numbering of the vertical set of vertical strings, starting at the left towards the right, counting 1^(st) to last vertical strings).

Substantially equal-length sets of strings, like opposing diagonal strings, disperse the impact of the ball more evenly around the frame than a conventionally-strung racket because the equal-length sets of opposing diagonal strings vibrate at an equal frequencies and thus the racket, is more balanced. As a result, a diagonally-strung racket is more comfortable to use, and lessens the impact transmitted to the player's hand, arm, wrist, elbow and shoulder, thereby protecting the player's hand, wrist, arm, elbow, and shoulder from undue stress. Orthopedists, physical therapists and avid tennis players have confirmed that a diagonally-strung racket results in fewer injuries to the player. Moreover, radar speed guns have measured the serving speed of a ball hit by a diagonally-strung racket to be 15% faster than a ball being served by a player who was using a conventionally-strung frame.

The string-length measurements shown above are for a typical oversize tennis racket being strung in a vertical-horizontal configuration, and a diagonal stringing configuration, would hold true, with similar string-length relationships, in all game rackets where the vertical and horizontal centerlines of the racket head are unequal in length. All such rackets, when strung, would result in conventional stringing patterns that have string sets that are unequal in length, as compared to diagonally-strung configurations, where the opposing string lengths are equal in length. These relationships hold true in all such tennis rackets, such as those that have racket head sizes which are considered to be small, midsize, super-midsize, oversize, or super-oversize, and applicable to the entire selection of rackets, of various head sizes, in other game rackets for other racket sports, such as in racquetball rackets, squash rackets, and badminton rackets. For game rackets with a circular head shape, the strings lengths would not be as important a factor, since the vertical and horizontal centerlines of the racket head would be generally equal, however for such circular head-shaped rackets, being diagonally-strung, would still provide a superior, more-balanced dispersion of the impact around the frame, because typically there would not be any vertical strings, and forces would not be transmitted along vertical vectors which would be more apt to transmit vibration straight downward, towards the player's hand. If the impact was transmitted along diagonal vectors, the diagonal stringing pattern would spread out the vibration more, and improve the dispersion of the impact and arguably lessening the impact transmitted to the player's arm, shoulder, wrist, elbow and hand.

Offering the player the ability to string the frame conventionally as well as diagonally, may expand the customer base to include players who have mastered conventional stringing and are not interested in diagonal stringing but like the opportunity to try it out, with the knowledge that they can also string the racket of the present invention conventionally and not waste their money if they decide to keep it conventionally-strung rather than strung in a diagonal pattern. Some players do not want to use diagonal stringing; however, if a player likes the balance, weight and frame-shape design of one of these convertible frames, but prefers conventional stringing, they can purchase this racket and string it in the conventional manner. Similarly, if a player likes the balance, weight and frame-shape design of one of these convertible frames, but prefers diagonal stringing, they can purchase this racket and string the racket of this present invention in the diagonal orientation. Thus, having the capability of stringing one racket in multiple stringing patterns will be beneficial, because a convertible racket will appeal to a broader range of players and be saleable to a broader base of players. In addition, if a player who prefers to use diagonal stringing breaks a string and finds himself somewhere where the stringer is unfamiliar with diagonal stringing, any racket stringer can very easily string this convertible racket in a conventional (vertical-horizontal) pattern, which every stringer, skilled in the art of stringing rackets, can do.

To make the stringing even easier, in a preferred embodiment of the present invention, the racket has dot-to-dot hole numbering information on the face of the frame, or some other indicia, indicating the directions for a conventional, vertical-horizontal stringing pattern. In a still more desired embodiment, the racket of the present may also have indicia, preferably distinct from the conventional stringing indicia, for diagonal stringing on either the other side of the racket, or on the same side. Such indicia make it easy for a stringer to string the racket of this invention in a conventional stringing pattern, in a diagonal stringing pattern, or in other pre-determined patterns. The stringer can string the racket in a conventional stringing pattern, with which he or she might be more familiar and comfortable doing. Additionally, if the player that bought said convertible racket wants the versatility of switching between different stringing patterns, for instance, if they have injured their arm using conventionally-strung rackets and want to try a pattern that may be more comfortable on the arm, the player can choose to have their convertible racket strung diagonally. It is believed that a diagonal stringing pattern will disperse the impact of the ball on the racket better and cause less vibration to be transmitted to the player's arm. Such a result is believed to be more comfortable to use.

Additionally, diagonal stringing is believed to increase the spin, speed and control of a ball hit by the racket so strung. Thus, a user might want to experiment with a racket that permits diagonal stringing. The racket of the present invention allows the player the choice of more than one stringing pattern, even though the player only purchases a single racket. Thus, the racket of the present invention has the stringing versatility equal to two or more rackets. One racket can offer a variety of playing characteristics because it can be strung up in more than one stringing pattern, and each player who purchases the racket of this invention can experience the benefits that each stringing pattern would offer. Instead of buying two rackets, the consumer can save money by purchasing one racket that can be strung in more than one way. Thus, the racket of the present invention is unique, and provides benefits not previously available.

In addition, a diagonal stringing pattern lasts longer than a conventional stringing pattern. It is believed that a diagonal stringing patter is a more stable pattern because the diagonals crossing one another form a more secure weave with less movement of the strings, than the strings experience in a conventional stringing pattern. It is further believed that in a diagonal stringing pattern, because of this lesser movement of the strings, there is less friction of strings rubbing against each other. As a consequence, it is believed that the strings in a racket strung in a diagonal pattern may last up to five times longer than the strings in a racket strung conventionally. Consequently, a player using a racket of the present invention could switch the stringing from a conventional pattern to a diagonal pattern if, in the conventional pattern, the strings were breaking too frequently.

The inventor found that it was not easy to determine how to take a conventionally-strung racket and re-string it diagonally while maintaining the stability of the frame, nor vice versa. One problem in attempting to string a racket in a pattern other than that selected by the manufacturer is that the string supports (the means for supporting the strings such as grommets, string hooks, clips, collets, apertures, holes or other such mechanisms) around the frame generally are not in the position necessary to facilitate stringing a racket in alternative stringing patterns such that the resultant strung racket that will be structurally sound when strung in a stringing pattern for which the racket was not initially designed. For each stringing pattern, the necessary frame and string support reinforcements and proper orientation and alignment of the string supports would not be in their proper places. Further, for each alternative stringing pattern, the necessary frame reinforcements and correct alignment and orientation of the string supports would not be in the proper locations to facilitate creating a structurally sound racket that would result in a non-distorted frame shape, when strung in a pattern other than the stringing pattern in which it was originally intended to be strung. Only the racket of the present invention has been designed so as to accommodate multiple stringing patterns In view of these considerations, unless the racket is manufactured to accommodate more than one stringing pattern, it cannot. Additionally, the correct inter-string spacing necessary for optimum performance will most likely not occur unless the racket was so designed and planned, in advance, to accommodate one or more alternative stringing patterns. If a stringer began with a conventionally-strung frame, it is not a trivial calculation to figure out at what angle the diagonals need to be inserted to maintain a balanced, structurally sound frame shape, and what parallel spacing between diagonal strings must be used to avoid undue stress or breakage of the frame.

The wrong angle of the diagonals will stress the frame, possibly to the point of breaking the frame, and the result will be a structurally unsound, deformed racket. The location of where to begin inserting the diagonal strings, and the steepness of the angle of diagonal strings are not readily apparent, and if not calculated correctly, will warp, or break, the frame when said unplanned diagonal stringing pattern is tensioned. Nor is it a simple matter to create a stringing pattern that is legal for tournament play. However, the racket of the present invention is designed to avoid any such calamities.

It has been discovered that some string supports which might be specifically angled for one type of stringing orientation, might have to be skipped in one or more stringing patterns to obtain the full benefit of the present invention. Consequently, it is preferred that there are helpful indicia around the frame to insure that the multiple arrays of stringing configurations are correctly created. In some embodiments, this result is obtained by following the dot-to-dot numbers or another coding system of indicia necessary to reference the various patterns in which each racket frame is capable of being strung. The racket of the present invention would allow ease of stringing in more than one stringing configuration, as the design details of this present invention have been carefully calculated and the benefit of those lengthy calculations are being made available to the player and the stringer via embodiments of the present invention.

PRIOR ART

Prior art rackets do not anticipate the racket of the present invention. In particular, the inventor is unaware of any racket frame that can successfully be strung in more than one stringing patterns, while still maintaining the structural stability of the frame, and not putting the frame hoop or strings under undue stress or tension. Instead, it is the inventor's experience that when a conventional racket is strung in a pattern other than the single stringing pattern suggested by the manufacturer, the racket frame assumes a shape distorted from the shape of that conventional racket before stringing said racket in a new stringing pattern for which the frame was not designed. In addition, the inter-string widths would be arbitrary and irregular. While rackets have been designed with unique string patterns, the present inventor is not aware of any racket that can be strung successfully in more than one configuration without putting undue stress on the racket frame; nor is the present inventor aware of any racket heretofore available that can be successfully strung in more than one configuration without distorting the shape of the frame or putting undue stress or tension on the string lengths or racket hoop.

As used herein, the term non-distorted shape refers to the ability of a strung racket to be substantially superimposed on top of an unstrung racket of the identical hoop shape, of the same variety of racket.

SUMMARY OF THE INVENTION

Broadly, the present invention is a game racket designed to be sequentially strung in more than one configuration, each configuration using a subset of some or all of the string supports necessary for a properly strung racket.

As used herein, the term “string supports” refers to structures generally located at least in part on the interior of the racket hoop, for securing the racket strings in position. Exemplary string supports include string supports, grommets, apertures, collets, hooks, holes or other such mechanisms. The location, angle, and preferably the indicia marking these string supports, are strategically calculated, designed and uniquely located around the frame such that said string supports can be used to create a plurality of stringing configurations in the racket of this present invention. In some embodiments of the present invention, there are only indicia for one of the more than one stringing pattern for which the racket of the present invention is suited. In other embodiments, there are more than one set of indicia for stringing the racket in more than one stringing pattern. For instance, one side of the racket head could have indicia (for instance, green letters) indicating the path of the string through the string supports to create a stable, diagonal stringing pattern; or for instance, on one face of the racket hoop one set of diagonals can be indicated by black indicia, while on that same face of the racket hoop, the opposing set of diagonals can be indicated by white indicia. In such an embodiment of the present invention, the other side of the racket head could have indicia (for instance, blue numbers) indicating the path of the string through the strings supports to create a stable conventional stringing pattern of horizontal and vertical string sets. In a further embodiment of the present invention, the side of the racket with the blue numbers could also have yellow Greek letters to guide the stringing of another alternative diagonal pattern of different diagonal widths, or alternatively, a three-directional stringing pattern or four-directional stringing pattern.

In a preferred embodiment of this invention, the strings are substantially outside of the racket handle.

BRIEF DESCRIPTION OF THE DRAWINGS

In the five drawings set forth herein:

FIG. 1 shows a front view of a racket, according to the present invention, strung in a diagonal stringing configuration;

FIG. 2 shows a front view of a racket, according to the present invention, strung in a horizontal and vertical stringing configuration;

FIG. 3 shows a front view of an unstrung racket, showing the horizontal and vertical centerlines of the racket hoop;

FIG. 4 shows a front view of a racket, according to the present invention, strung diagonally and includes tangential lines showing where to place string supports; and

FIG. 5 is an illustration that identifies the relative trigonometric relationships of angles, lines, mathematical notations and labels used in the formulas to calculate the specific angles of the diagonals and spacing between strings for diagonal stringing configurations.

DESCRIPTION OF A PREFERRED EMBODIMENT

It is a completely new idea for a racket to be capable of being strung in multiple stringing configurations. The racket of this invention is designed specifically to permit the player to alternate from one stringing pattern to another, and the player can choose which stringing pattern he or she prefers, all with the purchase of a single racket. Heretofore, a player wishing to go from a conventional stringing pattern to a diagonal pattern had to purchase a two rackets. With the racket of the present invention, the player can simply have their racket restrung in one or another stringing pattern. Thus, more players will be able to experience a variety of stringing pattern configurations without needing to purchase an additional racket or rackets.

In some embodiments of the present invention, the frame of the racket may have reinforcements. Materials are now available to create very strong frames, enabling various configurations which may not have always been available or used in rackets, and thus the idea of being able to string a racket in more than one configuration was not possible, nor anticipated, in the past. Now that synthetic and natural materials have been developed with greater strengthening characteristics than heretofore available, this unique concept of being able to sell one frame that can be strung in more than one stringing pattern is a versatile idea that has never been anticipated.

The racket of the present invention is desirably designed such that the angle of the intersecting strings and spacing between said strings will be so chosen as to further implement a structurally-sound frame shape, such that when the strung in each of the plurality of stringing patterns, the frame shape will not distort, i.e., the strung frame can be substantially superimposed upon the unstrung frame. Further, the string supports of the rackets of the present invention are in exact locations to accommodate more than one stringing pattern. It is further preferred that each stringing pattern is specifically designed, either symmetrically, or not. It is particularly preferred that in tennis racket embodiments of the present invention, the strings are at least as dense in the center of the frame as they are in any other area of the frame. This is a requirement imposed by international tennis regulations for tournament play.

One embodiment of the present invention provides a racket that can be converted from one stringing pattern to another with string supports at such exact locations and angles as to enable such various patterns to coexist sequentially. In a further embodiment, the racket of the present invention has indicia on one or both sides of the frame to assist in stringing pre-determined patterns.

In another embodiment of the present invention, string supports are placed about the frame so that the racket can utilize one type of stringing, then by changing the width between the strings from the first stringing pattern orientation, the stringing patterns would offer a variety of performance characteristics. The racket of the present invention provides the versatility of two or more rackets.

In a further embodiment of the present invention, the string supports of the racket can be strung in a diagonal stringing pattern (see FIG. 1) and subsequently can be strung conventionally, that is in a generally orthogonal array of horizontal and vertical sets of strings, (see FIG. 2), or vice versa. One example of why it is useful for the racket to have this versatility is if, for instance, a stringer was unfamiliar or unwilling to string rackets diagonally (see FIG. 1) or if the player wanted to use a racket strung in a conventional, generally orthogonal stringing pattern of vertical and horizontal sets of strings (see FIG. 2). The racket which heretofore was strung diagonally could subsequently be strung in said conventional, orthogonal pattern, as in the stringing pattern of FIG. 2.

Such string support placement should be calculated in advance of production of the rackets to ensure that the strings are in the proper locations and angled optimally to ensure the structural stability of the frame. Additionally, advance calculation permits the racket of the present invention to properly accommodate the more than one stringing patterns without deforming the racket shape. As a result, a player can use a single frame to obtain a variety of playability options. This would be a considerable cost savings to players and allow advanced versatility that has never been accomplished or designed before. Another embodiment would be to include indicia around the frame to assist in stringing said differing stringing patterns. Such indicia may be located on the same or different sides of the racket frame, or may entail numbering or coding or coloring near or on the string supports to indicate the more than one stringing pattern associated with a particular frame. Alternatively, the indicia can identify which string supports need to be skipped in order to achieve the desired stringing pattern since in some, but not all embodiments of the present invention, a given stringing pattern will employ most, but not necessarily all of the string supports in the racket frame of the present invention. (See FIG. 2)

Broadly, the present invention is a racket with a plurality of string supports located around the frame such that said string supports can be strung up in more than one stringing configuration, producing a racket that can be converted from one type of stringing pattern to another or others. Additionally, there can be indicia on one or both sides of the frame to assist in stringing the racket to the desired configurations. Such a racket has never been designed and the racket of this invention is unique and not anticipated from any of the prior art.

More than one stringing pattern could be taught by using multiple sets of indicia on either side of the racket frame or elsewhere on the racket or promotional material. The racket can be placed in the stringing machine with one set of indicia facing upwards to follow the directions for one stringing pattern then on subsequent stringing the racket can be flipped over and placed in the stringing machine with directions for an alternative stringing pattern visible. It is a completely new idea and not anticipated by any of the prior art for a racket to be able to be strung in more than one configuration while still maintaining the structural stability of the racket frame, so strung. The racket of the present invention is designed specifically to permit the player to choose which orientation of stringing the player prefers, without purchasing multiple rackets to obtain various stringing configurations. On the frame, string supports are located to create two or more distinct stringing patterns. Such string supports are placed and aligned at exact locations, and there may be stringing pattern indicia around the frame to assist in stringing each unique, desired stringing pattern. These indicia are located on the same or different sides of the racket frame, or may entail coloring the grommets or other string support means to clarify the path of the string for each respective stringing arrangement.

Specifically, it is a feature of the invention that the racket can be strung diagonally, meaning the strings are interwoven in two opposite diagonal directions, with said opposite diagonal directions being oblique to the longitudinal axis of the frame handle. At a subsequent stringing of the frame, after the diagonal strings are removed, with the aid of the indicia located around the frame, strings can be inserted in a conventional, orthogonal pattern of verticals (mains) and crosses (horizontals). The indicia on the frame can indicate which string supports means can be used to complete a specific pattern in either a diagonal pattern, or a conventional pattern of horizontal and vertical strings or in a three-directional pattern, or four-directional stringing pattern. Said indicia are to assist in identifying the order and location of the strings of a particular stringing pattern. One or both side of the frames may or may not have indicia to assist in stringing a specific orientation of diagonal, orthogonal (conventional) stringing, three-directional or four-directional stringing patterns.

The structure of the frame must be such that the frame remains in a non-distorted shape when it is strung in the various stringing configurations. Other rackets may have string supports, but there are no prior art frames so designed that are capable of being strung in such diverse stringing patterns nor does any prior art suggest this capability of designing rackets that do not distort in a multitude of configurations. Upon stringing all prior art rackets in various configurations, such prior art frames would not maintain their original shape when subsequently strung in multiple stringing configurations of strings, as they were not designed to be so strung, and no prior art suggests the versatile racket design of the present invention. At a subsequent stringing of the frame, the diagonal sets of strings can be removed and by using the indicia, or not, the spacing of the diagonals can be adjusted to a greater or lesser width, or strings can be inserted in an orthogonal pattern of verticals (strings parallel to the handle of the racket, called mains), interwoven with horizontals (strings perpendicular to the handle of the racket, called crosses), or in a three-directional stringing pattern (two sets of opposing diagonals interwoven with either one set of horizontal or one set of vertical strings), or four-directional stringing pattern (two diagonal sets, one set of vertical and one set of horizontal strings.) The plurality of indicia on the frame can indicate which string support string supports can be used to complete a specific pattern in either a conventional manner of horizontal and vertical strings, in various densities of spacing between strings in either conventional orientations, diagonal configurations, or in three-directional or four-directional patterns. The structure of the frame might be constructed with reinforcements at strategic locations such that the frame remains in a general state of equilibrium, generally in a non-distorted state, and in a state that remains and produces a structurally-sound racket shape when it is strung in the various stringing configurations. Other rackets may have string supports but upon stringing them in various configurations such frames would not maintain their original shape, nor necessarily remain in a non-distorted shape when strung in a plurality of stringing pattern configurations, and would not necessarily be legal for tournament play as they might have strings that are generally uniformly spaced and not less dense in the center because the frame to which they are being inserted was not designed to be strung in a plurality of stringing pattern configurations. Therefore, in order to create a racket of this invention, a plurality of carefully placed string supports, perhaps with reinforcements, must be engineered to create the stringing patterns and be designed to precisely accommodate the tensions and stresses on the frame created by the multiple vectors of the multiple stringing patterns affecting the racket frame.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows one side of a racket (21) strung diagonally with two sets of interwoven diagonal strings (22) crossing at a certain angle (24) with indicia (23) around the frame marking the pattern and the string supports (13) to assist in creating said diagonal stringing pattern (22).

FIG. 2 shows the reverse side of the racket frame (21) of FIG. 1, having been re-strung using the indicia (14) on this reverse side (21) of the frame, with said indicia around the frame being different from the indicia (23) shown in FIG. 1. The indicia (14) on the side of the frame of FIG. 2 is to assist the stringer in stringing said frame in a conventional stinging pattern of horizontals and vertical strings (16), utilizing specified string supports (15) located around the frame at predetermined locations to enable said racket (21) of FIG. 1 to be converted, in this subsequent stringing, to said conventional stringing pattern of horizontal and vertical strings (16), intersecting at generally orthogonal angles (17), strung on the same frame (21) that in a prior stringing was strung in the diagonally-oriented stringing configuration of FIG. 1.

FIG. 3 shows the racket hoop (21) placed on the horizontal dotted centerline (32) and vertical dotted centerline (33), necessary to use when marking the points of intersection of the frame hoop of the horizontal centerline (34-Point A) and (35-Point B) and the vertical centerline (36-Point D) and (37-Point C), said centerlines intersect at Point J, useful when symmetrically lining up the racket (21) in order to calculate the location of FIG. 2 string support string supports (15) that are described in Example 2, Example 4 and FIG. 5.

FIG. 4 shows the diagonal stringing pattern (40) of the racket (21) of FIG. 3 as said stringing pattern intersects the curve (41) of the hoop of the racket head, necessary when calculating the location of the string support means of said diagonal stringing pattern embodiment. Those skilled in the art of racket production will note that the string support means are created such that each string is inserted into or attached to the frame at an angle that is generally perpendicular to the tangent of the frame at the point of intersection of the stringing pattern and the frame. The pattern in the racket head (41) is symmetric around the vertical dotted centerline, thus only the right hand set of aperture tangent lines (42) have been indicated on FIG. 4, since string supports to the left of the vertical centerline are the mirror image of the string supports to the right of the vertical centerline.

FIG. 5 identifies the labeling of the angles, diagonal string lines, and spacing between diagonal strings, referenced in the original mathematical formulas described in Example 2 and Example 4 herein. Dotted lines on FIG. 5 are horizontal and vertical centerlines used to calculate the stringing pattern; the thick dark lines represent the diagonal strings. Line segment FH is a line segment of horizontal centerline AB (32) of FIG. 3. Line segment GI is a line segment of vertical centerline CD (33) of FIG. 3. The trigonometric formulas described in Example 2 and Example 4 herein are necessary to calculate the angles of the diagonal strings and the spacing between strings of a diagonal stringing configuration, in order to determine the locations of the string support means of said diagonal stringing configuration, so as to create a diagonal stringing configuration that is both structurally sound, and in a non-deformed shape when strung diagonally, given any frame dimensions. The stringing configurations may also be adjusted to create symmetric or uneven spacing between the diagonal strings of a diagonal configuration.

EXAMPLE 1 Steps to Follow to Create the Prototype for a Racket with a Choice of Stringing Patterns

1. Using a T-Square to squarely attached graph paper to a drawing surface, or using another measuring device to insure proper orthogonal alignment, secure a piece of graph paper, for instance a 10×10 grid graph paper, which is graph paper that is divided into inches, then each inch of the graph paper is divided into tenths of inches, forming said 10×10 grid within each inch. These tenths of inches make it easier to transfer to the paper the measurements, in tenths of an inch, of spacing between strings and angle measurements, done by trigonometric, mathematical calculations, in inches.

2. Measure the horizontal and vertical center of the graph paper, and draw the vertical and horizontal centerlines.

3. Place an un-drilled or unstrung racket frame, which is a head mounted on a handle, that may or may not have string supports, be it string supports, grommets, collets, holes, apertures, hooks or other such mechanisms, and center said racket frame around those vertical and horizontal centerlines, such that the handle of the racket is parallel to the vertical centerline, and the end of the butt cap is centered around the vertical centerline, and the hoop is centered both vertically and horizontally around the respective centerlines; then secure the racket onto the graph paper (See FIG. 3).

4. Inner and outer outlines of said racket are traced onto the paper. The points where the horizontal and vertical centerlines intersect the inner outline of the hoop of the racket frame are so marked onto the frame. (See FIG. 3)

5. The intersection of the horizontal and vertical centerlines is marked point J. (See FIG. 3).

6. On the graph paper, the point where the inner part of the top of the hoop outline intersects the vertical centerline is marked point C, and the point on the drawing, at the inner bottom of the hoop outline, that intersects the vertical centerline, is marked point D. (See FIG. 3)

7. On the graph paper, where the left part of the inside of the hoop outline intersects the horizontal centerline is marked as point A, and the point on the drawing that the right part of inside of the hoop intersects the centerline is marked point B. (See FIG. 3).

8. Calculate the pattern of the diagonal pattern by either Example 2 and Example 4 both described below herein, or by using computer programs that calculate diagonal patterns, create a diagonal stringing pattern with spacing between diagonal strings having a perpendicular distance between strings of from 11 and 20 millimeters (mm). If the measurement is in millimeters, for ease of calculations and graphing the pattern, convert that measurement to inches. Once the pattern is determined, on the centerline mark off a distance of “y” inches above and below the centerline, then continuing from those points on the centerline, mark off distances of “X” inches, until the centerline is so divided up into “X” length units, then using the T-square and an angle measurement set to the value of Angle GFJ described in FIG. 5 and Example 2 and Example 4, draw opposing diagonals through each of those “X” points, such that opposing, corresponding diagonals intersect on the vertical centerline.

9. Once the preferred pattern is determined and drawn onto the graph paper, place the frame back onto the graph paper and mark off on the frame where the diagonal pattern intersects the inner hoop of the frame. Starting at the top of the frame, follow the pattern of how one set of diagonals would be woven, making sure that the structural supports of the frame will not interfere with the looping of the strings. Once the efficacy of the pattern is determined, add indicia to the racket to denote the path of the string. Such indicia could include where to start stringing and where to end. (See FIG. 4).

10. Remove the racket, then on the same piece of graph paper, or on a transparent piece of graph paper placed on top of the original graph paper, measure out a grid for a conventionally strung frame of vertical and horizontal sets of strings. Those skilled in the art will know how to create said conventional grid.

11. Then flip over the racket frame that is marked on one side with markings to denote a diagonal string pattern, and, replacing said racket onto the graph paper, with the prior markings for the diagonal string pattern face down, and the side facing up having no prior markings, center said racket around the vertical and horizontal centerlines. Using those same vertical and horizontal centerlines on the graph paper, center and attach the racket onto the graph paper (See FIG. 3).

12. Mark the frame where the conventional strings would intersect the frame, making judgments of combining two holes together if the pattern is such that two holes would be too close, or make such holes into double holes, wide enough to encompass the location where the hole would need to be to placed to properly accommodate the string support for both patterns. Once the pattern is determined, mark the frame at those locations where the pattern intersects the innermost portion of the hoop, and add indicia to denote the path of the string. Such indicia could include where to start stringing and where to end and tie knots or similar ending configurations of the strings. (See FIG. 2).

13. If one of the orientations desired is a three-directional pattern, or a differently spaced pattern of diagonal or conventional configurations, once the pattern is drawn and determined, mark the intersection of that pattern onto the hoop of the frame then, and indicia may or may not be added to denote the path of the string. Such indicia could include where to start stringing and where to end.

14. Add string support structures, such string supports are defined very generally as a structure located at least in part on the interior of the racket hoop, including holes, string supports, hooks, or similar fasteners, for securing strings in position.

15. For those skilled in the art of stringing rackets, string the racket using indicia on one side of the hoop of the frame (see FIGS. 1 and 2), then upon subsequent stringing, remove the strings and the same racket (see FIGS. 1 and 2) can be strung using the indicia on the opposite side of the hoop of the frame, such that the pattern created is different from the one created when the racket was strung previously.

FIG. 5 identifies the labeling of the acute angles that intersect with the horizontal centerline in a range that is between 10 and 80 degrees, and the perpendicular distance between diagonal strings, labeled HK, that are in a range of between 2 mm and 29 mm.

Please refer to labels identified in FIG. 3 and FIG. 5 and mentioned in Example 2 and Example 4, herein described, and please note the geometric “Given” relationships shown in FIG. 5.

Given: FJ=JH=z FH=S 2z=S GJ=JL=y 2y=X GI=X

EXAMPLE 2 Finding the Distance Between Intersecting Diagonals on the Vertical Centerline, Once you have Chosen the Desired Perpendicular width Between Diagonals

#1. Measure the internal horizontal and vertical dimension at the midlines of the ellipse of the racket head, and divide each of those dimensions by 2, to get the value of CJ and AJ. (See FIG. 3) $\begin{matrix} {{{{\# 2}.\quad{Calculate}}\quad{the}\quad{tangent}\quad{of}\quad{Angle}\quad C\quad A\quad J} = \frac{{side}\quad{opposite}}{{side}\quad{adjacent}}} \\ {= \frac{C\quad J}{A\quad J}} \\ {= {{tangent}\quad{value}}} \end{matrix}$

#3. Find tan⁻¹ (On calculator press shift, and tan key, then “=” key, this gives the value of Angle CAJ, the angle the diagonals cross the center horizontal midline. Angle CAJ has the same value as Angle GFJ, since generally, in a diagonal pattern, diagonal angles, with respect to a horizontal midline drawn through their vertex, are congruent. Next, determine the Complimentary Angle of Angle CAJ and Angle GFJ, which is Angle JHK

For instance, if Angle CAJ=Angle GFJ=53° Complimentary Angle of 53°=(90−53)=37°

#4. Next, choose the desired perpendicular distance HK, in millimeters, converted to inches, between diagonals. ${{Cos}\quad J\quad H\quad K\quad{^\circ}} = {\frac{{side}\quad{adjacent}\quad\left( {H\quad K} \right)}{{hypotenuse}\quad{``S"}} = \frac{H\quad K}{S}}$ ${hence},{S = \frac{H\quad K}{{Cos}\quad J\quad H\quad K\quad{^\circ}}}$ ${{Next}\quad{solve}\quad{for}\quad S},{{{then}\quad\frac{S}{2}} = {{z\quad{thus}\quad\left( \frac{1}{2} \right)(S)} = z}}$ ${{{{\# 5}.\quad{Tangent}}\quad{of}\quad{Angle}\quad G\quad F\quad K} = \frac{y}{z}};{{{thus}\quad y} = {\left( {{Tan}\quad G\quad F\quad J} \right)(z)}}$ Solve  for  y, then  X = 2y

“X” is the vertical distance on the center midline between intersecting diagonals.

Start measuring from the center horizontal line in both directions a value of “y”, then after that, above and below the “y” measurement, measure out a value of “X”.

(See FIG. 5). Draw opposing diagonal lines through those points measured out on the vertical centerline, setting the angle measurement to the angle at which the diagonals cross the horizontal centerline.

EXAMPLE 3 A specific Case Using Methods Described in Examples 1 and 2

-   -   #1. Measure the length and width of the racket. For instance,         the racket chosen has an inner hoop length along the vertical         centerline of 13.8 inches, and an inner hoop width along the         horizontal centerline measuring 10.4 inches     -   #2. The relationship of the vertical to horizontal centerlines         of the racket is:         $\frac{C\quad D}{A\quad B} = {\frac{13.8}{10.4} = 1.326923077}$         is the same relationship as $\frac{G\quad J}{F\quad J}$         which relationship are both the tangent of the Angle at which         the diagonals cross the horizontal centerline. $\begin{matrix}         {{{Tan}\quad{of}\quad{Angle}\quad C\quad A\quad J} = {{Tangent}\quad{of}\quad{Angle}\quad G\quad F\quad J}} \\         {= \frac{G\quad J}{F\quad J}} \\         {= \frac{{side}\quad{opposite}}{{side}\quad{adjacent}}} \\         {= 1.326923077}         \end{matrix}$     -   Knowing that the value of the tangent of Angle GFJ is         1.326923077 we can then determine the numeric value of Angle         GFJ.     -   #3. The tan⁻¹ GFJ=1.326923077=52.99742559° or approximately         53°=Angle GFJ.     -   The complementary angle is 37.00257441°=0.7986084685     -   #4. Next, choose a perpendicular distance between diagonal         strings of 15.5 mm, Which equals 0.61 inches, =HK. Angle         JHK=37.00257441°         ${{Cos}\quad J\quad H\quad K\quad{^\circ}} = {\frac{{{side}\quad{adjacent}\quad\left( {H\quad K} \right)}\quad}{{hypotenuse}\quad S} = \frac{H\quad K}{S}}$         Cos  37.00257441^(∘) = .798608468         ${hence},\quad{S = {\frac{H\quad K}{{Cos}\quad J\quad H\quad K\quad{^\circ}} = {\frac{.61}{.798608468} = {S = {.763828615}}}}}$         ${{then}\quad{since}\quad\frac{S}{2}} = {{z\quad{thus}\quad z} = {{\left( \frac{1}{2} \right)({.763828615})} = {z = {.381914307}}}}$         ${{{\# 5}.\quad{Tangent}}\quad{of}\quad{Angle}\quad G\quad F\quad K} = {{\frac{y}{z}\quad{thus}\quad y} = {\left( {{Tan}\quad G\quad F\quad J} \right)(z)}}$         ${{Tan}\quad{of}\quad{Angle}\quad G\quad F\quad J} = {1.327044822 = {\frac{y}{z} = \frac{y}{.381914307}}}$         Solve  for  y:  y = (1.327044822)(.381914307) = .50681743         then  X = 2y; thus  X = (2)(.50681743) = 1.013634806  inches     -   “X” is the vertical distance on the center midline between         intersecting diagonals. Start measuring from the center         horizontal line in both directions a value of y=0.5068 inches,         then after that, above and below the “y” measurement, measure         out a value of “X”=1.0136 inches (See FIG. 5). Draw opposing         diagonal lines through those points measured out on the vertical         centerline, setting the angle measurement equal to the         approximate 53° angle at which the diagonals cross the         horizontal centerline.

EXAMPLE 4 To Find the Perpendicular Distance Between a Certain Number of Desired Diagonals in each Direction

-   -   #1: Calculate Angle GFJ following steps 1-3 above, and referring         to FIG. 3 and FIG. 5.     -   #2 Referring to FIG. 3, for 16 diagonals, measure CD, the inner         vertical distance on the vertical centerline then divide CD by         (16-3) to get “X”; for 17 diagonals, divide by (17-3) to get         “X”. Always divide by a number that is 3 less than the desired         number of diagonals. SO, for a pattern of 16 diagonals in each         direction: CD divided by the (number of diagonals −13)=X     -   #3: Since ${\frac{X}{2} = y},$         then solve for y     -   #4: Since Tangent of Angle GFJ= ${{GFJ} = \frac{y}{z}},$         next solve for $z = {\frac{y}{{Tan}\quad G\quad F\quad J}.}$     -   #5: Since 2z=S, solve for S     -   #6: Since,         ${{{Cos}\quad{Angle}\quad J\quad H\quad K\quad{^\circ}} = {\frac{H\quad K}{S} = \frac{{side}\quad{adjacent}}{hypotenuse}}},{{{then}\quad H\quad K} = {(S)\left( {{Cos}\quad J\quad H\quad K\quad{^\circ}} \right)}}$     -   #7: To solve for HK=the perpendicular distance between         diagonals, multiply by the numerical value of Cos JHK° by the         value obtained for “S” in Step 5 of this Example 4.

EXAMPLE 5 To Find the Perpendicular Distance Between a Certain Number of Desired Diagonals in Each Direction, Using Directions Described in Example 4

-   -   #1.1: Following Steps # 1-3 of Example 2 above, said steps         herein respectively labeled. #1.1, #1.2, and #1.3, measure the         length and width of the racket, as shown in FIG. 3.     -   For instance, the racket chosen has an inner hoop length along         the vertical centerline of 13.8 inches, and an inner hoop width         along the horizontal centerline measuring 10.4 inches. Please         refer to FIG. 3 and FIG. 5 for these calculations.     -   #1.2: The relationship of the vertical to horizontal centerlines         of the sample racket is:         $\frac{C\quad D}{A\quad B} = {\frac{13.8}{10.4} = 1.326923077}$         which is the same relationship as $\frac{GJ}{FJ},$         both of which are the tangents of the Angle at which diagonals         cross the horizontal centerline (See FIG. 5). $\begin{matrix}         {{{Tan}\quad{of}\quad{Angle}\quad{CAJ}} = {{Tangent}\quad{of}\quad{Angle}\quad{GFJ}}} \\         {= \frac{GJ}{FJ}} \\         {= \frac{{side}\quad{opposite}}{{side}\quad{adjacent}}} \\         {= 1.326923077}         \end{matrix}$     -   Knowing that the value of the tangent of Angle GFJ is         1.326923077, then the numeric value of Angle GFJ can be         determined.     -   #1.3: Tan⁻¹ GFJ=1.326923077=52.99742559° or approx. 53°=Angle         GFJ.     -   The Complementary Angle of Angle GFJ° is an Angle FHK, measuring         37.00257441°, or approximately 37°         #2: Referring to FIG. 3, with a desired stringing configuration         of 16 diagonals in each direction, since CD measures 13.8         inches, the inner vertical distance on the vertical centerline,         then,         divide CD by (16−3)=13, thus 13.8 divided by 13=1.061538461=X         #3: For 17 diagonals, divide by (17-3) to get a smaller X,         meaning the spacing between strings would be less. Always divide         by a number that is 3 less than the desired number of diagonals.         So, for a pattern of 17 diagonals in each direction:         CD/14=0.9985714285=X, representing the centerline delineations         between intersecting diagonals on the vertical centerline. The         example below is for 16 diagonals in each direction, calculating         the value of X=1.061538461         #4: Since X/2=y then 1.061538461 divided by 2=0.53076923=y         ${\# 5}:\begin{matrix}         {{{Since}\quad{the}\quad{Tangent}\quad{of}\quad{Angle}\quad{GFJ}} = \frac{GJ}{FJ}} \\         {= \frac{{side}\quad{opposite}}{{side}\quad{adjacent}}} \\         {= 1.326923077}         \end{matrix}$         ${{{then}\quad\underset{\_}{{Tangent}\quad{of}\quad{Angle}\quad{GFJ}}} = \frac{y}{z}},{{thus}\quad\begin{matrix}         {z = \frac{y}{{Tan}\quad{GFJ}}} \\         {= \frac{.53076923}{1.326923077}}         \end{matrix}}$ Thus, z = .399999999

#6. Since 2z=S, solve for S, thus S=(2)(0.399999999)=0.799999998 ${\# 7}.\begin{matrix} {{{Since}\quad{Cos}\quad{Angle}\quad{JHK}^{{^\circ}}} = \frac{{side}\quad{adjacent}}{Hypotenuse}} \\ {= \frac{HK}{S}} \end{matrix}$ ${{{then}\quad{Cos}^{{^\circ}}37.00257441} = \frac{HK}{S}},{{{thus}\quad{HK}} = {(S)\left( {{Cos}\quad{JHK}^{{^\circ}}} \right)}}$ #8. To solve for HK=the perpendicular distance between diagonals, multiply the numerical value of Cos JHK° by the value obtained for “S”

-   -   The Cos of JHK=Cos Angle 37.00257441°=0.7986084685     -   Thus (S)(Cos JHK)=(0.799999998)(0.7986084685)=0.6388867732=HK     -   The perpendicular distance between strings, for a diagonal         stringing configuration with 16 diagonals in each direction,         would be equal to a distance of 0.6388867732 inches.

Prior art rackets are not capable of utilizing a plurality of stringing patterns nor can they be convertible from one structurally sound stringing configuration to another. Rackets of this invention can be strung in multiple configurations that can include diagonal stringing and then subsequently said frames can be strung in a conventional, orthogonal orientation of mains and crosses or in a three-directional or four-directional pattern of stringing, or such frames can be designed for multiple diagonal angle and/or varying density of width between strings in either conventional or diagonal configurations upon subsequent stringing of the racket. In the present invention, one or both sides of the rackets may or may not have indicia to assist in stringing a specific orientation of stringing. Said indicia are to assist in identifying the order and location of the strings of a particular stringing pattern and never have rackets been made with the concept of providing a choice of stringing patterns being achieved or designed with string support locations so situated so as to accommodate multiple stringing configurations. This invention is unique, is not anticipated from prior art, since new engineering was necessary to accomplish the end product. This invention would be useful in the marketplace for many players who conveniently would now have a choice of stringing patterns that heretofore has never been available or engineered. It is a completely new idea and not anticipated by any of the prior art for a racket to be able to be strung in multiple configurations while still maintaining the structural stability of the racket frame. The convertible racket of this invention is designed specifically to permit the player to choose among orientations or configurations of stringing patterns, without purchasing multiple rackets to obtain the advantages of said various stringing configurations.

While the invention has been particularly shown and described with reference to specified embodiments hereof, it will be understood by those skilled in the art that there are changes in form and details that may be made herein without departing from the spirit and scope of the invention. 

1. A sports racket comprising: A) a frame portion defining a rounded opening of predetermined shape with a vertical axis and a horizontal axis, said frame further comprising: String supports positioned to support at least two different stringing patterns; a plurality of indicia effective to guide the stringing of said frame; and B) a handle portion secured to said frame.
 2. A sports racket frame comprising: A) A first set of string supports positioned about said frame to support, without distorting said frame, a first stringing configuration; and B) A second set of string supports positioned about said frame to support, without distorting said frame, a second stringing configuration Wherein at least one of said string supports of said first set is not a member of said second set and at least one of said string supports of said second set is not a member of said first set.
 3. A sports racket comprising: A) A frame according to claim 2; and B) A handle.
 4. The sports racket frame of claim 2 further comprising a plurality of indicia to guide the stringing of said frame using said first set of string supports.
 5. The sports racket frame of claim 4 further comprising a plurality of indicia to guide the stringing of said frame using said second set of string supports.
 6. The sports racket frame of claim 2 further comprising strings attached to said frame using said first set of string supports wherein the strings intersect at angles between about 10° and 170°.
 7. The sports racket frame of claim 2 further comprising strings attached to said frame using said first set of string supports wherein at least some of the strings intersect at angles between about 30° and 90°.
 8. The sports racket frame of claim 2 further comprising strings attached to said frame using said second set of string supports wherein at least some of the strings intersect at angles between about 50° and 90°.
 9. The strung sports racket frame of claim 6 wherein each string is separated from the closest parallel string by a distance of between about 5 millimeters to 30 millimeters.
 10. A sports racket comprising: A) a racket handle portion secured to a frame; and B) said frame portion defining a rounded opening of predetermined shape with a vertical axis and a horizontal axis, said frame further comprising: i) At least two sets of string supports, each of said sets of string supports positioned to support at least two different stringing patterns, wherein, said sets of string supports are in said racket frame, such that when the handle of said racket frame is oriented vertically, at least one of the stringing patterns, of said sets of string supports, have two sets of opposing diagonal sets of strings, obliquely oriented with respect to the vertical axis of the handle of said racket, such that said opposing sets of diagonal strings intersect in a range of downward facing angles of between about 30 and 110 degrees; and, ii) A plurality of indicia effective to guide the stringing of said frame.
 11. The sports racket of claim 10 wherein said downward facing angle is between about 52 and 92 degrees.
 12. The sports racket of claim 10 wherein said downward facing angle is between about 60 and 84 degrees.
 13. The sports racket of claim 10 wherein said downward facing angle is between about 67 and 77 degrees. 